Question

Which of the following is the correct order of the penetrating power of alpha ($\alpha$), beta ($\beta$) and gamma rays ($\gamma$)?

• A. $\alpha <\beta >\gamma$
• B. $\alpha >\beta >\gamma$
• C. $\alpha <\beta <\gamma$
• D. $\alpha =\beta =\gamma$

Answer 1

The correct option is C $\alpha <\beta <\gamma$

Penetrating power refers to the energy with which the radiation particles are ejected from an atom. The higher the energy, the more the particles or rays produced by radioactive decay will penetrate a substance.

• Alpha particles have the least penetrating power. They cannot penetrate through air for more than 8-10 cm.
• Beta particles have more penetrating power than alpha particles, upto a few metres in air.
• Gamma rays have the most penetrating power, upto a few hundred metres in air.

Therefore, the order of penetrating power is $\alpha <\beta <\gamma$.